Choosing Wisely:

Avoid ordering Vitamin D concentrations routinely in otherwise healthy children, including children who are overweight or obese.

Although a 25-hydroxyvitamin D concentration, reflecting both vitamin D synthesis and intake, is the correct screening lab to monitor for vitamin D deficiency, current evidence is not sufficient to suggest that screening in otherwise healthy children who are overweight or obese is necessary or safe.
Global consensus recommendations caution against population-based screening for vitamin D deficiency The U.S. Preventive Services Task Force also has noted that variability of current assays and unclear cutoffs for deficiency may lead to “misclassification” of persons as having vitamin D deficiency, and that this misclassification could outweigh any benefits if there are harms. The AAP report on Optimizing Bone Health in Children and Adolescents advises screening for vitamin D deficiency only in patients with disorders associated with low bone mass such as rickets and/or a history of recurrent, low-trauma fractures.
It has been shown that children who are overweight or obese have a greater likelihood of having low vitamin D levels. If the history suggests an obese child has insufficient dietary intake of vitamin D (e.g., little milk intake), a vitamin D supplement should be recommended, which is more cost-effective than 25-hydroxyvitamin D measurements for both screening and monitoring therapy.